Intake of a component with a high antioxidative effect, such as vitamins, polyphenols, and carotenoids, is a usual method for increasing antioxidative capacity in vivo. In recent years, a technique has been developed for enhancing antioxidative capacity in vivo by increasing the amount of an antioxidant enzyme produced in vivo. For example, the following methods have been proposed for this purpose: a method for treating immune system cells with Western dandelion-derived polysaccharide (Non-patent Literature (NPL) 1); a method for treating immune system cells with Nostoc commune-derived scytonemin (NPL 2); and a method for eating an isohumulone or an isomerized hop extract (Patent Literature (PTL) 1). Natural products may be extremely expensive and the effects achieved by natural products may vary depending on the production lot (PTL 2 to PTL 5). Further, such natural products are generally unstable under light or heat. When natural products are incorporated into foods or beverages and used, a stability problem arises. Further, natural products are poorly soluble in water and are thus difficult to use for beverages, etc., (PTL 6 to PTL 8). Furthermore, an extract of a natural product contains multiple compounds and the active principle of a natural product may not be clearly identified (PTL 1).
Glycogen is known as a reserve polysaccharide in animals. Glycogen is a highly-branched polymer in which many glucose molecules are polymerized by α-1,4 and 1,6 glycosidic linkages. Glycogen is mainly produced in the liver and skeletal muscles and functions as temporary storage of excess glucose.
Patent Literature (PTL) 9 discloses that enzymatically synthesized glycogen comprehensively improves the blood glucose level, visceral fat level, blood cholesterol level, neutral fat level, etc.
Further, Patent Literature (PTL) 10 discloses a method for producing enzymatically synthesized glycogen.
Further still, Patent Literature (PTL) 11 discloses an external preparation for the skin, comprising enzymatically synthesized glycogen. However, the antioxidative effect of enzymatically synthesized glycogen is not disclosed therein.